A “no-clean” solder flux material is a flux that is designed to be sufficiently volatile or that undergoes thermal decomposition to volatile products such that a cleaning step may not be necessary to remove flux and associated residues after a soldering operation. In some cases, a no-clean solder flux material may cause electrical failures when the solder flux material does not reach sufficiently high temperatures to completely volatilize a solvent carrier and to convert dicarboxylic acids to a clear, glassy state. If the solvent carrier is not completely volatilized, the solder flux material may remain in a resin-like state, enabling movement of ions and potentially resulting in electrochemical migration or dendrite formation.
The aforementioned issues associated with no-clean solder flux material may be particularly problematic in hand soldering and rework operations, in which the entire printed circuit board is not exposed to solder reflow temperatures. For instance, during a rework operation, solder flux material may move into other areas on the printed circuit board that are adjacent to the rework region. When the rework region is heated during soldering, distal areas where the solder flux material has moved may not reach solder reflow temperatures. Due to insufficient heating, the solder flux material in such distal areas may not be able to attain its glassy state, potentially resulting in corrosion and/or electrical failures. Additionally, entrapment of solder flux material beneath electrical components may also be problematic due to the additional time required for the solvent carrier to escape.